Archduchess Eilika (née Duchess of Oldenburg), wife of Archduke George of Austria (second son of the late Archduke Otto, and brother of the current Head of the Imperial and Royal House of Habsburg-Lorraine, Archduke Charles) was seen several times wearing a large pendant including a beautiful hexagonal aquamarine:
In October 1997, for George and Eilika's wedding in Budapest:
In August 2011 in Potsdam, at the wedding of Prince George-Frederick of Prussia and Sophie of Isenburg: